This invention relates to a rotating electrical machine which is used as either a motor or a generator, or both.
Rotating electrical machines used in various types of vehicles are provided with a structure to cool a stator in order to suppress heat generated in the stator as a result of conduction in the stator coils. Tokkai Hei 10-336966 published by the Japanese Patent Office in 1998 discloses a structure which is provided with cooling liquid passages (through holes) passing through the stator in a direction parallel with the rotational axis of the rotor. The passages cool the stator by allowing flow of a cooling liquid, namely a cooling medium.
However this conventional structure entails the problems that it is difficult to form a cooling liquid passage which has a sufficiently large contact surface area with the stator to allow a strong cooling effect. The conventional technique entails the further problem that the cooling liquid passage hinders the flow of magnetic flux in the stator, and that machining the stator core is difficult due to forming the through holes.
It is therefore an object of this invention to provide a rotating electrical machine which performs effective cooling of a stator.
In order to achieve above object, this invention provides a rotating electrical machine having a rotor free to rotate about a rotating shaft, a stator comprising a stator core formed by laminating a plurality of magnetic steel plates in a direction parallel with the rotating shaft of the rotor and coils wound on the stator core, and the case storing the stator.
The rotating electrical machine comprising a cooling liquid passage defined by the outer peripheral face of the stator core and the inner peripheral face of the case, the cooling liquid passage extending parallel to the direction of the rotating shaft, wherein the stator core being cooled by passing a cooling liquid through the cooling liquid passage.
The details as well as other features and advantages of this invention are set forth in the remainder of the specification and are shown in the accompanying drawings.